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1. Field of the Invention
The present invention relates to harvesting machines and methods of harvesting and more particularly, to an improved method and apparatus for harvesting heads of lettuce. Even more particularly, the present invention relates to an improved method and apparatus for harvesting lettuce that features a dual paddle and actuator arrangement that quickly separates a head of lettuce from its root and stem, throwing it to a conveyor. In one embodiment, a sensor or manually operated switch initiates a timing sequence to activate the actuator. A pair of pneumatic cylinders actuate the paddles or flippers that are positioned on opposed sides of a head of lettuce to be picked. The paddles move at a speed that is sufficient to separate the head of lettuce from its stem and root, thrusting it above the underlying earth in an arcuate path to a waiting conveyor.
2. General Background of the Invention
Typically, the harvesting of lettuce has been a manual operation. However, some patents have issued for machines that purport to be lettuce harvesters. Early examples of lettuce harvester patents include U.S. Pat. Nos. 3,380,234; 3,380,237 and 3,497,013. Another example of an early patent is U.S. Pat. No. 3,731,477 entitled xe2x80x9cHarvester for Headed Vegetablesxe2x80x9d. The xe2x80x2477 patent discloses a high speed lettuce harvesting machine comprising a vehicle adapted to move along vegetable rows to be harvested, a pair of vegetable head-engaging sensing arms mounted on said vehicle, a plurality of sensor belts mounted on said arms, the sensor belts being adapted to be deflected by the circumference of said vegetable head to guide and actuate a cutting blade toward the stem of the vegetable head so as to sever only fully grown heads and to transport them to a conveyor.
U.S. Pat. No. 3,632,919 discloses an apparatus to detect mature heads of lettuce in a cropped row. The apparatus includes a mobile support movable along the row, and a support mounted above row vertically floatable detector unit bearing successively on the heads of lettuce as the support moves, the detector unit including a gauge and detector wheel assembly.
U.S. Pat. Nos. 3,800,518 and 3,827,503 show tractor mounted lettuce harvesters.
An apparatus for removing loose and/or excess leaves from the head of a leafy edible plant is disclosed in U.S. Pat. No. 3,821,987 entitled xe2x80x9cLettuce Harvesting Apparatusxe2x80x9d. The apparatus includes a conveyor means for conveying the head after the stump has been removed therefrom, with the residual stump portion arranged at the bottom of the head and with the sides of the head unencumbered, whereby the outermost excess leaves fall by gravity from the head during transport from a first position to a second position. In one embodiment, the head is supported solely between the parallel vertically-spaced adjacent runs of upper and lower endless conveyor means, the horizontal run being less than the diameter of the head, whereby the removal of the excess leaves is greatly facilitated with the aid of gravity. The second position may be higher than the first position, in which event the adjacent parallel runs of the upper and lower conveyors are inclined to the horizontal, thereby further assisting in leaf removal. In a second embodiment, the head is supported by generally horizontal conveyor means that include a pair of parallel spaced adjacent longitudinal runs between which are arranged selectively operable cutter means for trimming the residual stump portion of a head and thereby effect removal of excess leaves therefrom.
In U.S. Pat. No. 4,094,238, there is provided a lettuce harvester having a positive means for engaging the stems of lettuce to be trimmed whereby the trim cut is caused to take place at right angles to the stem, and the lettuce is left ready for packaging.
The Lenker U.S. Pat. No. 4,136,509 discloses an apparatus for harvesting vegetable heads. A sensing means including a pair of parallel, laterally movable, head-engaging units, which are counter-rotated, is fixed to a frame. A cutting means is mounted on the frame and is responsive to the sensing means. The cutting means includes a horizontal knife blade rotatable 180 degree for each head cut. The severed head is removed from the cutting area by a pair of counter-rotating lifter belts.
The Gray U.S. Pat. No. 4,876,844 discloses a field crop harvesting, carton packaging and packed carton handling machine, which includes transport means having a front section, central section and a trailing section. The front and trailing sections include a ground engaging means and each include a platform mounted on the ground engaging means. The front platform also includes an area for stacking and supplying non-erected cartons and for erecting non-erected cartons. The central section includes a conveyor support including a central conveyor means and a left and right conveyor means. The left and right conveyor means each include erected carton receiving and supplying means. The left and right conveyor means include a series of carton packing stations as well as a conveyor for moving the packed cartons to a central conveyor. The control conveyor includes a rearwardly moving conveyor for transporting packed cartons rearwardly to the trailing platform. The trailing platform includes an area for receiving, handling and sealing the packed cartons and distributing the sealed cartons. The apparatus also includes the method of harvesting, carton packaging and packed carton handling together with the steps of cleaning the crop and sealing the same in the cartons.
U.S. Pat. No. 5,310,102 is entitled xe2x80x9cApparatus for Field Sleeving of Lettuce and Other Vegetablesxe2x80x9d. The ""102 patent discloses a vegetable sleever suitable for field wrapping of vegetables such as leaf lettuce at the time of harvesting in order to prevent shipping damage.
The Ottaway (applicant herein) U.S. No. 5,560,190 is entitled xe2x80x9cLettuce Harvesting Method and Apparatus to Perform Samexe2x80x9d. The ""190  patent discloses a method for the automated harvesting of headed row crops, including lettuce, optionally leaving at least the crop root in the ground, and an apparatus to practice the method. The present invention provides a methodology to locate crop stems, separate the outer leaves from the head, grip the stem and harvest the head. Gripping the stem is accomplished with at least one pneumatic gripping bladder. Substantially simultaneous to gripping the head, the head is separated from the core and stem. One method to accomplish this separation is by means of a pair of differential pneumatic bladders which frees the head from the core at the center of the head, leaving the core and the outer leaves attached to the stem and root. Alternatively, a second separation method taught herein is the application of a downward force applied to the top of the head by a pneumatic bladder. The two separation schemes may be used conjointly or in the alternative. As a further alternative, the present invention teaches a harvesting method which cuts the stem at the core, leaving the core within the head and the outer leaves attached to the stem and root. After harvesting, a conveyor means removes the produce to a bin or other receptacle.
U.S. Pat. No. 6,050,073 discloses a harvester and method of harvesting leafy vegetables. The disclosed harvester is designed to harvest vegetables which are delicate and are grown in precisely configured beds of either a rectangular or singular width or a double width. A conveyor/cutter assembly is located on one side of the harvester centerline and has a width somewhat exceeding the width of a single width bed. The wheels on each side are separated by somewhat more than the width of a double bed. The driver and engine is located on the other side of the centerline. Such a harvester can cut single width beds, or can cut double width beds by making a first pass in one direction and a second pass in the other direction. An improved single conveyor/cutter assembly is disclosed along with a method of harvesting and processing leafy vegetables to reduce the amount of debris and unwanted material in the harvested leafy vegetables.
The present invention provides an improved method and apparatus for harvesting lettuce, preferably two or more rows at a time. The lettuce harvester of the present invention includes a frame and a plurality of ground engaging supports. One of the supports is a central support that travels between two rows of lettuce during use. This central ground engaging support is preferably an endless belt-type track.
A plurality of paddles are movably supported upon the frame, including preferably a pair of paddles for each row of lettuce to be harvested. The paddles are positioned on opposing sides of a row to be harvested so that two opposed paddles move toward each other and engage the underside of the head of lettuce to be harvested.
A powered linkage is provided for moving the paddles between lower and upper positions. As the paddles travel swiftly from the lower to the upper position, they engage and pick a head of lettuce to be harvested.
In the preferred embodiment, one of the paddles engages the head of lettuce to be harvested before the other paddle engages the head of lettuce. The time for striking the head of lettuce is delayed slightly for the second paddle, causing the head of lettuce to be separated from its root and stem and to be thrust upwardly and laterally in an arcuate path to a conveyor. The xe2x80x9clate hitxe2x80x9dby the second paddle imparts a lateral travel component to the head of lettuce, sending it toward the conveyor.
An actuator mechanism is provided that moves the paddles at selected time intervals, the actuator operating the powered linkage to move the paddles in a very fast, arcuate path. In the preferred embodiment, the paddles are preferably pivotally attached to the frame.
The paddles move at a speed sufficient to thrust each harvested head of lettuce upwardly a distance above the soil of preferably at least 15 inches and preferably between about 15 and 40 inches.
The lettuce harvester of the present invention can include a deflector that alters the travel path of any head of lettuce that elevates too far after it is picked by the paddles. The deflector can be in the form of an arcuate cage that extends from a position above the paddles to a position above the conveyor.
The apparatus can include a sensor that senses when a head of lettuce is engaged by the machine as it travels forward. The sensor can be a mechanical member carried by the frame that contacts each head of lettuce sequentially as the harvester moves forward.
In the preferred embodiment, the sensor engages each head of lettuce and is deflected away by the head of lettuce. This deflection of the sensor activates a switch that initiates a timing sequence. In this fashion, the sensor determines when the paddles are to be operated in order to harvest each sequentially encountered the next head of lettuce.